Pharmacology Unit 4 Flashcards by Kristen Stahl

selective toxicity-define

feature of antibiotic therapy as effects of antimicrobial agents should be exerted on microbe and not host.
targets biochemical differences between pathogen target and host–>exploitation of these differences

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selective toxicity-examples

-inhibition of metabolic pathway in bacteria but not humans–folate metabolism (metabolize intracellularly, mammals take up from environment)

-pathways that exist in both but are different in enzyme structure–protein synthesis (bacterial ribosomes that are 30 and 50S vs. 40 and 60S.
nucleic acid synthesis (DNA gyrase vs topoisomerase)

macromolecular structure doesn’t exist in humans (cell wall synthesis, peptidoglycan component)
macromolecular structure differs between humans and microbes (fungal cell membrane-ergosterol)

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narrow vs. extended vs. broad antibacterial spectrum: basic definitions of the 3

narrow spectrum–most effective on susceptible organism, less disturbance of host flora. GRAM POSITIVE OR NEGATIVE

broad spectrum–sacrifice efficacy for greater scope of activity for initial empiric coverage, more likely to cause superinfections. GRAM POSITIVE AND NEGATIVE

extended spectrum–effective against gram positive and gram negative

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narrow antibacterial examples (gram + or -)

aminoglycosides
penicillinase-resistance penicillins
clindamycin
vancomycin
metronidazole
penicillin g, v

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extended antibacterial examples (gram + and -)

extended-spectrum penicillins
cephalosporins
fluoroquinolones (cip, levo)
carbapenems

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broad antibacterial examples (gram + and - and atypical)

macrolides
chloramphenicol
fluroquinolones (moxi, gemi)
sulfonamides
tetracyclines
trimethoprim

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resistance: chromosomal vs. plasmid mediated

mutational (chromosomal) resistance: effect varies, multiple generations must happen to see appreciable resistance. proper dosing prevents survival of slightly resistant strains

plasmid mediated resistance: extrachrosomal pieces of circular DNA, carrying genetic information that can confer resistance. source of multiple drug resistances that can emerge in 1 course of treatment

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resistance: mechanisms

natural

natural (intrinsic) resistance: microbes lack susceptible target for drug action
-(fungal cell walls don’t have peptidoglycan and mycoplasma have no walls).

pseudomonas auerginosa is intrinsically resistant to many antibiotics (can’t cross the membrane)

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resistance: mechanisms

escape

microbes are sensitive and antibiotic reaches target but organism “escapes” consequences due to availability of purines, thymidine, serine, methionine released from purulent infections (sulfonamide resistance)

failure to lyse due to lack of osmotic pressure difference (penicillin resistance)

importance drainage surgical procedures

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resistance: mechanisms

acquired

selective pressure (antibiotic administration) produces generations of organisms with biochemical traits that minimize drug action

mutational
plasmid

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resistance: implications for therapy

can be minimized by only using antibiotic when needed, select based on susceptibility tests, use adequate concentration and duration to prevent emergence of first and second step mutants.

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classifications of antimicrobial mechanisms of action

altered targets
enzymatic destruction
alternative resistant metabolic pathway
decreased entry 
increased efflux

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bactericidal agents vs bacteriostatic agents definitions

bactericidal: organisms are killed
bacteriostatic: organisms are prevented from growing

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bactericidal mechanisms

inhibition of cell wall synthesis
disruption of cell membrane function
interference with dan function/synthesis

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bacteriostatic mechanisms

inhibition of protein synthesis (exception is aminoglycosides, -cidal)
inhibition of intermediary metabolic pathways

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advantages of bactericidal agents

preferred in severe infections (assuming sensitive organism, drug distribution, drug safety)
act more quickly, action is often irreversible (sustained effect after drug is eliminated from blood)
compensate for patients with impaired host defense (diabetes, etc.)
required for treatment of infections in locations not accessible to host immune system responses (endocarditic vegetation, CSF)

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importance of pharmacokinetic and host factors in selection of antimicrobial therapy

consider pharmacodynamics (antimicrobial activity against specific organism), pharmacokinetic properties (absorption from route of administration), distribution (to site of infection), elimination (hepatic or renal) as related to duration of antimicrobial activity

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absorption (oral vs. parenteral vs. topical)

oral: advantage of ease, acceptance, lower cost. can cause GI upset/diarrhea, if NPO.

IV: needed for some drugs/patients has advantage of most rapid/predictable plasma levels (treating life-threatening infections). disadvantage needed with IV are greater training, expense, specific antiseptic conditions

switch to oral whenever and whenever possible

infections can be managed with local application of antibiotic (skin or mucus membranes)

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distribution (CNS penetration, fetal exposure, selective accumulation-beneficial vs. harmful)

once antibiotic has been absorbed into systemic circulation must be distributed

CNS: most antibiotics distribute to tissue outside CNS, vary based in ability to cross BBB.

fetus: adverse effects may occur in the fetus that cross placenta. can be given orally, and have ability to cross gastric and placenta

selective-accumulation: certain antibiotics can result in harmful/beneficial response
beneficial: clindamycin into bone, treat osteomyelitis. concentrations of macrolides into pulmonary cells (upper respiratory infections). tetracyclines into gingival crevicular fluid. rapid excretion of nitrofurantoin

selective-increase toxicity: include amino glycoside binding to cells of inner ear, brush border. results increased ototoxicity, nephrotoxicity, tetracyclines-bind to developing bone and teeth to result in abnormal bone growth

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elimination

renal: alerts to possibility of renal dosing if necessary in patients with kidney dysfunction. process where dose and frequency are adjusted based on renal function. measure SCr and CrCl
hepatic: possibility of drug-drug interactions or hepatotoxic antibiotics. no lab value to give estimate of liver function

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drug classes eliminated by renal excretion

require dosage adjustment if impaired
penicillins
cephalosporins
vancomycin
aminoglycosides
fluoroquinolones

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drug classes eliminated by non renal mechanisms-use your mnemonic!!!

DQ CRIME
Doxycycline: non-regally eliminated tetracycline
(Q)uinolones: ciprofloxacin is really eliminated, but is non-substrate inhibitor of P450 (caffeine-theophylline)
Clindamycin: non-regally eliminated
Rifampin: inducer of P450, potential hepatotoxicity
Isoniazid: genetic polymorphism of n-acetyl transferase metabolism, potential hepatotoxicity
Metronidazole: drug-drug interaction with alcohol due to inhibition of aldehyde metabolism (Antabuse reaction)
Erythromycin-like: drug-drug interactions due to inhibition of P450 (Clar-Ery, not Azi)
Sulfonamides: n-acetylated to a more lipid-soluble metabolite-concern for renal crystalluria

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strep pneumoniae

pneumonia, otitis media, sinusitis

cocci-gram +

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strep pyogenes

pharyngitis

cocci-gram +

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viridans streptococci

endocarditis | cocci-gram +

staph aureus

(MSSA, MRSA) cutaneous infection, pneumonia, bacteremia, device associated infections cocci-gram +

enterococcus faecium-faecalis

bacterimia, intraabdominal infections, UTI | cocci-gram +

neisseria gonorrheae

gonorrhea | cocci-gram -

neisseria meningitidis

meningitis | cocci-gram -

ecoli

utis, intra-abdominal infections, lower respiratory infections, bacteremias, traveler's diarrhea rods- gram -

pseudomonas aeruginosa

noncosomial infections at any site (UTI, pneumonia) | rods- gram -

clostridium difficile

pseudomembranous colitis | anerobes-gram + rod

clostridium perfringens-botulinim-tetani

anerobes-gram + rod

bacteriodes fragilis

intraabdominal and brain abcess | anerobes-gram - rod

clamydia

trachoma, community acquired pneumonia, urethitis | atypical

mycoplsma pneumoniae

community acquired pneumonia | atypical

side effects: direct toxicity

antibiotic effect on microbes affects host cellular processes (lack of selective toxicity) - varies with drugs and concentrations - can be mild/life threatening - usually involves GI tract, liver, kidney, nervous system, blood and blood forming system

side effects: indirect toxicity

``` allergic reactions, hypersensitivity salt effects (salt administered with antibiotic not antibiotic) drug-drug interactions, may alter CYP450 drug metabolizing enzymes ```

side effects: superinfections

disturbances in ecological balance of microbial community allows for overgrowth of normally suppressed pathogenic organism pseudomembranous colitis due to clostridium difficile overgrowth more commonly associated with broad spectrum antibiotics increased if 50, pulmonary disease, prolonged duration

cell wall synthesis inhibitors: penicillins-prototype

penicilin G

cell wall synthesis inhibitors: penicillins- acid stable

penicillin V

cell wall synthesis inhibitors: penicillins- penicillinase resistant

dicloxacillin

cell wall synthesis inhibitors: penicillins- extended spectrum

amoxicillin +/- clavulanate | ampicillin +/- sulbactam

cell wall synthesis inhibitors: penicillins- anti-pseudomonal

peperacillin-tazobactam

cell wall synthesis inhibitors: penicillins- beta-lactamase inhibitor

clavulanic acid | tazobactam

cell wall synthesis inhibitors: cephalosporins- 1st

cefazolin | cephalexin

cell wall synthesis inhibitors: cephalosporins-2nd

cefuroxime

cell wall synthesis inhibitors: cephalosporins- 3rd

cefriaxone | ceftazidime

cell wall synthesis inhibitors: cephalosporins- 4th

cefepime

cell wall synthesis inhibitors: cephalosporins- 5th

ceftaroline

cell wall synthesis inhibitors: cephalosporins- carbapenems

``` ertrapenem imipenem-cilastin meropenem doripenem VANCOMYCIN ```

protein synthesis inhibitors- macrolydes

erythromycin clarithromycin azithromycin

protein synthesis inhibitors-tetracyclines

tetracycline | doxycycline

protein synthesis inhibitors-others

clindamycin | chloramphenicol

protein synthesis inhibitors-aminoglycosides

know characteristics of class-not individual agents

inhibitors of DNA function- fluoroquinolones

ciprofloxacin levofloxacin moxifloxacin

inhibitors of DNA function-other

nitrofurantoin metronidazole trimethoprim-sulfamethoxazole

Bacteria develop resistance to tetracyclines by which primary mechanism? ``` Altered ribosomal target Bypass pathway in folic acid metabolism Enzymatic inactivation Increased drug efflux Mutations of DNA gyrase ```

Increased drug efflux == MDR gene

Which of the following is the primary mechanism of β-lactam antibiotic resistance with Streptococcus pneumoniae? Modification of drug target Decreased intracellular drug levels due to changes in permeability Decreased intracellular drug levels due to an efflux pump Enzymatic inactivation of drug

Modification of drug target

Which of the following antibiotics are considered to exert bactericidal actions against most organisms in their spectrum at readily attained clinical levels? ``` Tobramycin - AG Vancomycin - GP Ceftriaxone 3rd C Clindamycin Azithromycin - MAC Levofloxacin - urFQ ```

Tobramycin - AG Vancomycin - GP Ceftriaxone 3rd C Levofloxacin - urFQ

All of the following influence the penetration and concentration of an antibacterial agent in the cerebrospinal fluid EXCEPT: Lipid solubility of the drug Minimum inhibitory concentration of the drug Protein binding of the drug Molecular weight of the drug

Minimum inhibitory concentration of the drug

A 58-year-old male with a history of hepatitis C, cirrhosis, and ascites presents with spontaneous bacterial peritonitis. Which of the following antibiotics may require close monitoring and possible dosage adjustment in this patient given his liver disease? ``` Penicillin G - nPCN Tobramycin - AG Metronidazole Clindamycin Levofloxacin - urFQ Cephalexin - 1st C ```

Metronidazole | Clindamycin

Which drug increases the hepatic metabolism of other drugs? ``` Azithromycin - MAC Erythromycin - MAC Ketoconazole - AF Tobramycin - AG Rifampin - TB Metronidazole ```

Rifampin - TB

The persistent suppression of bacterial growth that may occur after limited exposure to some antibacterial drugs is called: ``` Clinical synergy Concentration-dependent killing Post antibiotic effect Sequential blockade Time-dependent killing ```

Post antibiotic effect

Which of the following antibiotics exhibits concentration-dependent killing? ``` Tobramycin - AG Vancomycin - GP Ceftriaxone 3rd C Clindamycin Azithromycin - MAC Levofloxacin - urFQ ```

Tobramycin - AG | Levofloxacin - urFQ

Which of the following agents is considered a narrow-spectrum agent? ``` Ceftriaxone - 3rd C Levofloxacin - urFQ Amoxicillin - ePCN Tobramycin - AG Doripenem - CARB Penicillin V - nPCN ```

Tobramycin - AG | Penicillin V - nPCN

Antimicrobial prophylaxis has been used in which of the following clinical situations? Tuberculin skin test converters Recurrent urinary tract infections Recurrent genital herpes simplex infections Gastrointestinal surgical procedures Healthcare workers exposed to blood after needlestick injury Dental patients with artificial heart valves undergoing extractions

Tuberculin skin test converters Recurrent urinary tract infections Recurrent genital herpes simplex infections Gastrointestinal surgical procedures Healthcare workers exposed to blood after needlestick injury Dental patients with artificial heart valves undergoing extractions

Antibiotics are commonly administered before surgical procedures. Which of the following statements best describes an appropriate use for perioperative antimicrobial prophylaxis? Begin antibiotic prophylaxis at least 24 hours before surgery Include an antifungal in the regimen Select the broadest spectrum antibiotic for complete coverage Use antibiotic combinations as opposed to monotherapy Administer the antibiotic just prior to the procedure

Administer the antibiotic just prior to the procedure

When using combination antibiotic therapy, it is important to administer drugs that work synergistically if possible. Which of the following represents a combination with known synergism? A penicillin and a cephalosporin Two drugs that work on the same step Two drugs in which the second drug will displace the first from plasma protein-binding sites A beta-lactam and an aminoglycoside Two drugs that are eliminated by different routes A sulfonamide with a dihydrofolate reductase inhibitor

A beta-lactam and an aminoglycoside | A sulfonamide with a dihydrofolate reductase inhibitor

A 24-year-old pregnant woman presents to the urgent care clinic with fever, urinary frequency and urgency. She is diagnosed with a urinary tract infection (UTI). Based on potential harm to the fetus, which of the following medications should be avoided in treating her UTI? ``` Nitrofurantoin Amoxicillin - ePCN Cephalexin - 1st C Gentamicin - AG Trimethoprim-sulfamethoxazole ```

Gentamicin - AG | Trimethoprim-sulfamethoxazole

Which of the following antibiotics is considered safe to use in neonates? ``` Chloramphenicol Sulfamethoxazole-Trimethoprim Doxycycline TCN Ampicillin - ePCN Ceftriaxone - 3rd C ```

Ampicillin - ePCN | Ceftriaxone - 3rd C

In a patient suffering from pseudomembranous colitis due to C. difficile with established hypersensitivity to metronidazole, the drug most likely to be of clinical value is: ``` Ampicillin - ePCN Clindamycin Doxycycline - TCN Levofloxacin - urFQ Vancomycin ```

Vancomycin

The primary mechanism of antibacterial action of the penicillins involves inhibition of: ``` Beta-lactamases Cell membrane synthesis N-acetylmuramic acid synthesis Reactions involving transpeptidation Porin insertion into membranes ```

Reactions involving transpeptidation

Methicillin-resistant Staphylococcus aureus is a common nosocomial pathogen that is increasing in frequency in community settings. Which of the following best describes the most common mechanism of resistance to methicillin by S. aureus? ``` Increased synthesis of metabolic factors Reduced permeability to beta-lactams Acquisition of the novel protein PBP2a Increased cell wall repair Increased efflux of beta-lactams ```

Acquisition of the novel protein PBP2a

Select the FALSE statement concerning use of ampicillin: Antibacterial activity is enhanced by sulbactam Causes maculopapular rashes Drug of choice for Listeria monocytogenes infections Eradicates most strains of methicillin-resistant Staphylococcus aureus May cause pseudomembranous colitis with extended use

Eradicates most strains of methicillin-resistant Staphylococcus aureus

A 23-year-old male presents with acute appendicitis that ruptures shortly after admission. He is taken the OR for surgery, and post surgical cultures reveal E. coli and Bacteroides fragilis. Which of the following provides adequate empiric coverage of these two pathogens? ``` Tobramycin - AG Vancomycin Ceftriaxone - 3rd C Piperacillin-tazobactam - apPCN Clindamycin ```

Piperacillin-tazobactam - apPCN

Select the FALSE statement concerning penicillin G: It is eliminated from the body primarily by renal excretion. It has reliable antimicrobial activity against most gram positive cocci. It is less reliably absorbed following oral administration than penicillin VK. It is effective in treating infections caused by penicillinase-producing organisms. It is more effective in killing rapidly growing bacteria than bacteria in the stationary phase.

It is effective in treating infections caused by penicillinase-producing organisms.

A 20-year-old female presents to the emergency department with headache, stiff neck, and fever of 2 days duration and is diagnosed with bacterial meningitis. Which of the following agents is the best choice for treatment of meningitis? ``` Acyclovir Piperacillin-tazobactam - apPCN Ceftriaxone - 3rd C Cefotaxime - 3rd C Tobramycin - AG Cefazolin - 1st C ```

Ceftriaxone - 3rd C | Cefotaxime - 3rd C

A 21-year-old man was seen in a clinic with a complaint of dysuria and urethral discharge of yellow pus. Gram stain of the urethral exudate showed gram-negative diplococci. The most appropriate treatment of gonorrhea in this patient is: Amoxicillin (ePCN) orally for 7 days Ceftriaxone (3rd C) intramuscularly as a single dose Tetracycline (TCN) orally for 7 days Benzathine penicillin G (nPCN) as a single intramuscular dose Vancomycin intramuscularly as a single dose

Ceftriaxone (3rd C) intramuscularly as a single dose

A major distinction between 1st and 3rd generation cephalosporins is: 3rd generation agents have less activity against Pseudomonas 3rd generation agents have increased activity against chlamydia 1st generation agents have increased penetration into the CNS 3rd generation agents have increased activity against resistant gram-negative organisms 1st generation agents have greater activity against methicillin-resistant Staphylococcus aureus

3rd generation agents have increased activity against resistant gram-negative organisms

A 45-year-old male presented to the hospital ED with severe cellulitis and a large abscess on his left leg. Incision and drainage were performed on the abscess, and cultures revealed methicillin-resistant Staphylococcus aureus. Which of the following antibiotics would be appropriate for this infection? ``` Ceftaroline - 5th C Piperacillin-tazobactam - apPCN Vancomycin Ceftriaxone - 3rd C Doxycycline - TCN Clindamycin ```

Ceftaroline - 5th C Vancomycin Doxycycline - TCN Clindamycin

Amoxicillin (ePCN) shares all of the following properties with cephalexin (1st C ) EXCEPT: ``` Inhibition of cell wall synthesis Bactericidal action Elimination primarily by the kidneys Beta-lactam ring in structure High susceptibility to bacterial beta-lactamases ```

High susceptibility to bacterial beta-lactamases

Select the FALSE statement concerning inhibitors of cell wall synthesis: Second generation cephalosporins have good-to-excellent activity against anaerobic organisms. The concentration of penicillin G in the CSF is higher when administered to patients with meningococcal meningitis than it is when given to normal, uninfected patients. First generation cephalosporins have greater activity against Pseudomonal infections than third generation cephalosporins. First generation cephalosporins (e.g., cefazolin) should not be given to patients with a Type I anaphylactic reaction to amoxicillin.

First generation cephalosporins have greater activity against Pseudomonal infections than third generation cephalosporins.

Which of the following adverse reactions is associated with vancomycin? ``` Teratogenic effects Red man syndrome Ototoxicity QT prolongation Severe GI upset Nephrotoxicity ```

Red man syndrome Ototoxicity Nephrotoxicity

Vancomycin: ``` Is bacteriostatic Binds to penicillin-binding proteins Is active against MRSA Has advantage of oral bioavailability Requires dosage reduction in renal impairment Is inactivated by beta-lactamases ```

Is active against MRSA | Requires dosage reduction in renal impairment

Select the FALSE statement concerning the bio-disposition of beta-lactam antibiotics: 1st generation cephalosporins cause the blood-brain barrier poorly even when the meninges are inflamed Lability of some penicillins in gastric acid can limit their oral absorption Ceftriaxone (3rd C) is eliminated by both renal and biliary-fecal excretion Benzathine penicillin G (nPCN) is used via intramuscular injection The renal tubular reabsorption of amoxicillin (ePCN) is inhibited by probenecid

The renal tubular reabsorption of amoxicillin (ePCN) is inhibited by probenecid

A 25-year-old male, otherwise healthy, comes to your office with symptoms of nasal congestion, clear rhinorrhea, and headache of 4 days duration. He reports that he was treated with penicillin V for strep throat as a 10 year-old with no adverse responses. Six weeks ago he received a single IM dose of ceftriaxone for a gonococcal infection. Current clinical guidelines suggest that a reasonable initial course of action should be treatment with: Azithromycin High dose amoxicillin Amoxicillin plus clavulanate Oral 3rd generation cephalosporin (Cefdinir-Omnicef) Ibuprofen as needed for pain and saline nasal lavage

Ibuprofen as needed for pain and saline nasal lavage

The primary mechanism of resistance of gram-positive organisms to macrolide antibiotics is: Decreased activity of uptake mechanisms Decreased permeability of drug through cytoplasmic membrane Synthesis of drug-inactivating acetyltransferases Synthesis of esterases that hydrolyze the lactone ring Methylation of drug binding sites on the 50S ribosomal subunit

Methylation of drug binding sites on the 50S ribosomal subunit

Clarithromycin and erythromycin have very similar spectra of antimicrobial activity. Advantages of clarithromycin include: Does not inhibit drug metabolizing enzymes Eradicates mycoplasmal infections in a single dose Has greater activity against H. pylori Is active against methicillin-resistant strains of staphylococci Is active against strains of Streptococci that are resistant to erythromycin Greater duration of activity

Has greater activity against H. pylori | Greater duration of activity

A 24-year-old woman comes to a clinic with complaints of dry cough, headache, fever, and malaise for 3-4 days. She appears to have some respiratory difficulty and chest examination reveals rales but no other obvious signs of pulmonary involvement. However, extensive patchy infiltrates are seen on chest x-ray film. Gram stain of sputum does not show any bacterial pathogens. Patient has no history of serious medical problems. The patient is taking loratadine for allergies, multivitamins, and iron supplements. She is an avid consumer of coffee and caffeinated beverages. The initial diagnosis is community-acquired pneumonia and a suitable drug choice would be: ``` Amoxicillin Azithromycin Erythromycin Clindamycin Doxycycline ```

Azithromycin Erythromycin Doxycycline

If the patient with CAP were prescribed erythromycin you should advise her to: Avoid exposure to sunlight Avoid taking supplemental iron tablets Decrease her intake of caffeinated beverages Have her serum creatinine checked before starting therapy Temporarily stop the antihistamine

Decrease her intake of caffeinated beverages

Select the TRUE statement regarding the pharmacologic actions of macrolide antibiotics: Erythromycin use is associated with less GI upset than clarithromycin. Possess bactericidal action via irreversible inhibition of protein synthesis. Erythromycin can elevate plasma levels of co-administered drugs metabolized by CYP450. Erythromycin has a longer half-life and requires less frequent administration than clarithromycin. Macrolides are more effective than metronidazole against anaerobic infections.

Erythromycin can elevate plasma levels of co-administered drugs metabolized by CYP450.

A 26-year-old woman was treated for gonorrhea at a neighborhood clinic. She was treated with a single IM dose of ceftriaxone and given a prescription for oral doxycycline (100 mg bid x 7d). Two weeks later she returned to the clinic with a mucopurulent cervicitis. On questioning she admitted not having the prescription filled. The best course of action at this point would be to: Delay drug treatment until the infecting organism is identified Rewrite the original prescription for oral doxycycline Treat her in the clinic with a single oral dose of amoxicillin Treat her in the clinic with a single oral dose of azithromycin Write a prescription for oral erythromycin for 7 days

Treat her in the clinic with a single oral dose of azithromycin

A 5-year-old kindergarten student presents with headache, fever, and cough of 2 days duration. Sputum is scant and nonpurulent and a Gram stain reveals many white cells but no organisms. Since this patient appears to have atypical (mycoplasmal) pneumonia, you should initiate treatment with: ``` Azithromycin (Zithromax) Doxycycline Cephalexin (Keflex, a 1st generation cephalosporin) Chloramphenicol Either A or B ```

Azithromycin (Zithromax)

A 19-year-old woman with recurring sinusitis has been treated with different antibiotics on several occasions. During the course of one such treatment she developed a severe diarrhea and was hospitalized. Sigmoidoscopy revealed colitis and pseudomembranes were confirmed histologically. Which of the following drugs is mostly to have caused this superinfection? ``` Clindamycin (Cleocin) Clarithromycin (Biaxin) Metronidazole (Flagyl) Penicillin V K Vancomycin ```

Clindamycin (Cleocin)

Doxycycline is: Bactericidal Excreted mainly in the urine Eliminated rapidly and is dosed 4 times a day More effective than tetracycline against H. pylori Recommended therapy for community-acquired pneumonia

Recommended therapy for community-acquired pneumonia

A patient is being discharged from the hospital on a 3-week course of clindamycin. Which of the following potential adverse effects should be discussed with her? ``` Nephrotoxicity Drug interactions due to enzyme induction C. difficile diarrhea Skin rash Ototoxicity ```

C. difficile diarrhea

Regarding the mechanism of action of aminoglycosides, the drugs: Are bacteriostatic Bind irreversibly to the 30S ribosomal subunit Cause misreading of the code on the mRNA template Inhibit peptidyl transferase Cause breakup of polysomes

Bind irreversibly to the 30S ribosomal subunit Cause misreading of the code on the mRNA template Cause breakup of polysomes

An aspirate from a peritoneal abscess grows two organisms. One is Escherichia coli while the other has the following characteristics: Gram-negative bacillus, obligate anaerobe, catalase-positive, and possesses a polysaccharide capsule. From your recommended training in microbiology you recognize this organism is most likely Bacteroides fragilis. From your required training in pharmacology you know that antibiotics with activity against such an anaerobe include all of the following EXCEPT: ``` Cefoxitin (2nd generation cephalosporin) Clindamycin (Cleocin) Metronidazole (Flagyl) Gentamicin, an aminoglycoside Piperacillin-Tazobactam ```

Gentamicin, an aminoglycoside

All of the following statements about the clinical uses of the aminoglycosides are accurate EXCEPT: They are effective in the treatment of Pseudomonal infections Owing to their polar nature, aminoglycosides are not absorbed after oral administration MRSA are usually sensitive to aminoglycosides Antibacterial action is concentration-dependent Ototoxicity due to aminoglycosides includes vestibular function and is often irreversible The earliest sign of aminoglycoside-induced nephrotoxicity is an increased blood creatinine

MRSA are usually sensitive to aminoglycosides

A 30-year-old pregnant female has cellulitis caused by MRSA. Which of the following would be the most appropriate option for outpatient therapy? ``` Amoxicillin-clavulanate Ceftaroline Clindamycin Doxycycline Minocycline Vancomycin ```

Clindamycin

You notice that an otherwise healthy patient has developed a mild case of oral candidiasis (thrush) while receiving antibiotic treatment for a respiratory infection. Which of these drugs is a broad-spectrum antibacterial agent that would most likely have caused this fungal superinfection? ``` Penicillin V Dicloxacillin Doxycycline Clindamycin (Cleocin) Clarithromycin ```

Doxycycline